Gas phase polymerization of propylene is one of the most widely accepted commercial processes, usually carried out in the presence of titanium-magnesium based ziegler-natta catalysts. The use of Ziegler-natta catalysts provides polymers/polyolefins with broad particle size distribution (100-5000 μm). The catalyst attrition during the polymerization process is predominantly responsible for the broad particle sizes distribution of polymers. The polymerization catalyst disintegrate during the polymerization process as the forces of the growing polymer chains fragment the catalyst. Each of the polymer fragments imprisons the catalyst fragment within itself and further grows in the reactor. Therefore, shape regularity and size distribution of polymer particles are directly related with the shape and size distribution of catalyst particles.
The controlled particle size distribution and shape regularity of polymer particles with reduced contents of polymer-fines is particularly desired for smoother plant operation and better throughput.